Diazotype materials for blackline images

ABSTRACT

Sensitizing agents for ammonia vapor developable black-line twocomponent diazotype sensitizing formulations comprising diazotized derivatives of 4-N-pyrrolidinyl-3-alkylparaphenylenediamine are employed with a mixture of coupling components which include an acetoacetamide, a naphthol, a diresorcyl compound alone or also with resorcinol.

United States Patent [191 Slimowicz et al.

[ Jan. 15, 1974 DIAZOTYPE MATERIALS FOR BLACKLINE IMAGES [75] Inventors: Chester Slimowicz; Walter J. Welch,

both of Binghamton, NY.

[73] Assignee: GAF Corporation, New York, NY.

[22] Filed: Apr. 26, 1972 [21] Appl. No.: 247,903

Related US. Application Data [63] Continuation of Ser. No. 56,186, July 10, 1970, abandoned, which is a continuation of Ser. No. 624,999, March 22, 1967.

[52] US. Cl 96/75, 96/49, 96/91 R [51] Int. Cl G030 l/54, G030 1/58 [58] Field of Search 96/91, 49, 75

[561' References Cited UNlTED STATES PATENTS 2,350,843 6/1944 Vonselow et a1. 96/91 R 2,688,543 9/1954 Von Glahn et a1.

2,717,832 9/1955 Sulich 3,203,803 8/1965 Habib et a1. 96/91 R Primary Examiner-Charles L. Bowers, Jr. Attorney-Samson B. Leavitt et a1.

[5 7] ABSTRACT Sensitizing agents for ammonia vapor developable black -line two-component diazotype sensitizing formulations comprising diazotized derivatives of 4-N- pyrrolidinyl-3-alkyl-paraphenylenediamine are employed with a mixture of coupling components which include an acetoacetamide, a naphthol, a diresorcyl compound alone or also with resorcinol.

8 Claims, No Drawings DIAZOTYPE MATERIALS FOR BLACKLINE IMAGES This is a continuation of application Ser. No. 56,186, filed July l0, 1970, now abandoned, which is a continuation of Ser. No. 624,999 filed Mar. 22, 1967.

The present invention relates in general to diamotype materials capable of yielding blackline images upon color development and more particularly to the utilization of specific light-sensitive diazo-coupler systems for such purposes.

As is well known, the diazotype materials currently available commercially and specifically adapted to the production of colored images, e.g., blue, red sepia, are legion. Although diazotype systems capable of yielding blue, red, green, i.e., non-black images, are in many instances advantageous, it is of critical importance in connection with the production of diazotype images contemplated for use as intermediates, i.e., for further exposures, that the image obtained possess optimum dye covering power and reprint capacity. The importance of these desiderata in such photographic applications'is at once apparent. As will be appreciated, it is of utmost importance that the intermediate diazotype material provide an image which is totally opaque to the actinic radiation contemplated for employment in connection with requiring operations utilizing such materials. Even slight departures from optimum covering power and reprint opacity are invariably manifested in the form of reduced contrast, density, etc., in the final print material. Heretofore, attempts to provide diazotype materials capable of yielding blackline images of the requisite superior reproduction quality have met with but marginal success. This is perhaps attributable to the fact that there is not available a single coupling compound capable of reaction with light sensitive diazonium compounds under the alkaline conditions employed for development to yield the desired black image. 7

As a result of the foregoing situation, the art has necessarily resorted to the use of coupler mixtures for the production of blackline images. For example, one of the coupler systems heretofore promulgated in this regard involves the use of at least three coupling components, i.e., capable of yielding a yellow green image, and a blue image respectively and a third or shading component capable of yielding a yellow brown image. Regardless of the particular system employed, it is nevertheless imperative that the several absorption spectra of the dye images yielded by the coupling compounds in question combine to yield a uniform and maximum absorption density across the entire visible spectrum. Thus, black image formation results since all incident visible radiation is absorbed uniformly by the image in question. One such exemplary coupler-mixture system currently enjoying rather widespread commercial use involves the employment of resorcinol as the shading component, acetoacetanilide for producing yellowgreen image and 2,3-dihydroxy naphtalene-6-sulfonic acid to produce a blue image. The dye mixture obtained with the use of these particular coupling components results in a reasonable black color in the maximum density ranges and a desirable greenish-gray coloration in the lower tones. Despite the fact that the dye images available with the foregoing combination of particular coupling compounds have proved to suffice quite well for a large number of commercial applications, certain difficulties have nevertheless been encountered as regards specific applications, e.g., the production of fast printing blackline diazotype prints. To a great extent, the problems involved are associated in some manner with the relative instability upon storage of such diazotype materials, such problems becoming significantly more pronounced under even moderately warm, humid conditions of storage. In this connection, it has been ascertained, for example, that such storage conditions are conductive to a differential mi gration of the various components of the diazo sensitizing composition into the base material carrying same and particularly in those instances wherein the base is of a fibrous nature.

Without intending to be bound by any theory, it has nevertheless been postulated in explanation of the foregoing that the resorcinol component of the coupler system, due to its relatively low molecular weight and high water solubility, exhibits a distinct susceptibility to migrate or otherwise diffuse into porous, e.g., fibrous materials. This correspondingly reduces the amount of coupling component available for image formation upon the alkaline-induced developing operation. This situation gives rise to very serious problems since there results an imbalance in the color aspect of the final image thereby vitiating substantially any attempt to achieve the desired black coloration. In the vast majority of instances, photographic reproductions produced with such diazotype materials are quite difficult if not impossible to distinguish from the conventional blueline diazotype prints. In essence, the print obtained if contemplated for use as a master, intermediate, etc. fails to satisfy commercial requirements and thus must be rejected. The scope of operations with such diazotype materials quite obviously has been severly circumscribed and, practically without exception, can be employed efficaciously only in those instances wherein the base material employed is of a nonporous nature.

ln an attempt to overcome or otherwise ameliorate the foregoing and related problems, the art has resorted to a wide variety of remedial techniques. Thus, it has been suggested that further ingredients be included in the diazo sensitizing composition which serve to obstruct or otherwise retard spurious diffusion of one or more of the coupling components. Other remedial techniques envisage the use of specific structural arrangements, i.e., the positioning of diffusion barriers intermediate the sensitized layers and base. Although such techniques have provided some margin of improvement, it has nevertheless been ascertained in practice that the results are far from optimum. Moreover, such procedures have proved to be objectionable from an economic standpoint as well since the fabrication of specific and predetermined dizaotype materials or alternatively, the use of compounds which tend to promote diffusion resistance, can prove to be quite costly. A large part of the industrial activity in this regard has centered around the research and development of coupling components which would serve as suitable alternatives for resorcinol to thereby eliminate the objectionable features attending the use of such compounds. Significant achievement in this connection has been obtained by replacing the resorcinol coupling component in whole or in part by either diresorcyl sulfide or diresorcyl sulfoxide. The latter compounds are particularly advantageous since they are totally devoid of any appreciable tendency to diffuse or otherwise migrate into the fibrous structure of porous base materials. The foregoing observation has been corroborated by laboratory testing under humidity-aging conditions simulating natural shelf storage of several months. The results of such testing indicate unequivocally that coupler diffusion, i.e., the diresorcyl sulfide or diresorcyl sulfoxide was substantially non-existent since prints produced therewith remained a neutral black despite the rather severe environmental conditions extent during testing.

Despite the fact that blackline diazotype materials fabricated with coupling systems of the foregoing type, i.e., wherein diresorcyl sulfide or diresorcyl sulfoxide is employed in lieu of resorcinol with the remaining coupling components comprising, usually, acetacetanilide and 2,3-dihydroxynaphthalene-6-sulfonic acid, have nevertheless been ascertained to provide somewhat sub-optimum results in particular applications and especially in connection with fast printing processes specifically adapted for the production of blackline diazotype intermediates. High speed processing has, of course, assumed a position of premier commercial importance in view of the manifold demands being imposed upon photographic reproduction processing. With particular reference to diazotype reproduction, it has been determined in practice that a substantial number of the diazo-coupler systems heretobefore promulgated in the art for the more conventional processing are eminently deficient as regards the production of high quality images with the use of high-speed processing. In general, the images obtainable with the conventional diazo-coupler systems characteristically exhibit inferior contrast, density, with high speed processing. In order to extend the applicability of the known diazocoupler systems to high speed processing, it was imperative to resort to the use of additional ingredients in the sensitizing composition for purposes of Augmenting actinic response while maintaining any possibility of contrast, density, etc. being deleteriously affected. The requirements thus imposed have proved to be rather burdensome as well as costly and have correspondingly tended to circumscribe significantly the diazo processors scope of operations in the field of high speed processing.

Actually, the problems confronting the processor as regards the obtention of high quality blackline reproduction has been essentially twofold; firstly, the provision of blackline-forming diazo systems capable of yielding images having adequate dye covering power as well as reprint opacity and secondly, the provision of such systems beneficially adapted to high speed processing.

In accordance with the discovery forming the basis of the present invention it has been determined that the high quality blackline reproductions characterizing the use of coupling systems containing as essential components, an acetoacetamide, 2,3-dihydroxy naphthalene- 6-sulfonic acid and a diresorcyl derivative, e.g., diresorcyl sulfide and diresorcyl sulfoxide, may be readily obtained despite the use of high speed processing conditions by the employment of such coupling systems in combination with a specific type of diazo sensitizing compound.

Thus, a primary object of the present invention resides in the provision of blackline diazotype materials wherein the foregoing disadvantages are eliminated or at least mitigated to a substantial extent.

Another object of the present invention resides in the provision of diazotype materials capable of yielding blackline images utilizing high speed processing said images being characterized by exceptional reproduction quality, i.e., contrast, density, etc.

A further object of the present invention resides in the provision of high speed blackline diazotype materials particularly and beneficially adapted for use in the production of intermediates, the images obtainable therewith exhibiting exceptional dye covering power and reprint opacity.

A still further object of the present invention resides in the provision of blackline diazotype materials wherein problems associated with the loss of coupler due to migration, diffusion, etc. of such materials into adjacent layers, and in particular to porous base materials are completely eliminated despite the utilization of such materials in high speed reproduction techniques,

Other objects and advantages of the present invention will become apparent hereinafter as the description proceeds.

The attainment of the foregoing and related objects is made possible in accordance with the present invention which, in its broader aspects includes the provision of blackline diazotype materials containing a coupling mixture comprising an acetoacetamide, a hydroxynaphthalene coupler selected from 2,3- dihydroxynaphthalene-6-sulfonic acid and a 2- hydroxy-3-(N-B-diloweralkylaminoethyl) naphthamide and a diresorcyl derivative selected from the class consisting of diresorcyl derivative selected from the class consisting of diresorcyl sulfide and diresorcyl sulfoxide and wherein the diazo component comprises a diazo derivative of a 4-N-pyrrolidinyl-3-alkylparaphenylenediamine of the following structural formula:

wherein R represents lower alkyl of one to four carbon atoms, i.e., methyl, ethyl, propyl, isobutyl, etc.

The improvements contemplated herein are realized to an optimum extent when R in the above formula represents methyl, i.e., 3-methyl-4-pyrrolidinylbenzendiazonium. The diamo and coupler materials described herein are known compounds with methods for their preparation being described in numerous publications both patent and otherwise. For example, diresorcyl sulfide can be readily prepared by reacting sulfur dichloride in ether, with resorcinol in ether at a temperature not higher than 12 C., neutralizing the reaction solution with sodium carbonate, stripping the ether from the organic layer and crystallizing the sulfide from water. Alternatively, the diresorcyl sulfoxide component may be compared from the sulfide by suspending it in water at 65 C. and oxidizing the sulfide with an excess of hydrogen peroxide at 6575 C.

The use of the stabilized 3-alkyl-4-pyrrolidinylbenzene-diazonium salts in combination with the aforedescribed mixture of couplers results in diazotype printing materials of the high speed variety which surprisingly and quite unexpectedly yield, after exposure and ammonia development, images which have a remarkably neutral black shade. In this respect our high speed combination of diazonium salt and couplers result in prints which are superior to those previously obtained and which did not show a neutral black but were characterized by a purpleblue hue.

It should also be mentioned that the present invention does not absolutely preclude the use of resorcinol as one of the coupling components since it has been ascertained that the undesirable features, e.g., diffusion, etc., characterizing this material are substantially nonexistent so long as the essential coupling components as well as diazonium compound previously described are present. Thus, resorcinol may be employed for purposes of complementing the shading action of the diresorcyl compound and to insure against any possibility of a shift in the image color to red.

The acetoacetamide couplers contemplated for use herein encompass the parent compound, i.e., acetoacetamide, as well as the N-substituted derivative thereof. Thus, the term acetoacetamide as used herein to be accorded the corresponding significance. Particularly beneficial results are obtained with the fast yellow" acetoacetamide derivatives, i.e., those containing N- alkyl or N-aryl bonded substituents. Coupler compounds of this type are well known in the art being extensively described in the literature both patent and otherwise. Although such definition encompasses a relatively wide variety of materials, investigation nevertheless indicates that optimum results invariably attend their use.

As particular examples of acetoacetamide coupler compounds coming within the foregoing definition there may be mentioned in particular the following:

Acetoacetanilide V N,N-ethylene-bis-acetoacetamide Acetoacet-a-naphthylamide mhydroxyacetoacetanilide o-methylacetoacetanilide o-methoxyacetoacetanilide p-methoxyacetoacetanilide 2-methoxy-5-methylacetoacetanilide N-(p-methoxybenzyl)acetoacetamide N-piperonylacetoacetamide N- l -indonylacetoacetamide N-(p-methoxyphenethyl)-acetoacetamide N-benzylacetoacetamide diacetoacet-dianisidide ....etc.

The diazo coating composition in addition to the above enumerated coupling and diazo components may contain any of the usual adjuncts conventionally employed in the manufacture of light sensitive diazotype materials. Such materials include, for example, metal salt for intensification of the dyestuff image, e.g., ammonium sulfate, methyl sulfate, zinc chloride and the like: stabilizing agents such as thiourea, thiosinamine, naphthalene, trisulfonic acid and the like; acid stabilizers to retard precoupling such as acetic acid, boric acid, tarteric acid and the like; wetting agents such as saponin, lauryl sulfonate, keryl benzene sulfonate, the oleic acid amide of N-methyl taurine, and the like. The 3-alkyl-4-pyrrolidinylbenzenediazonium salt is preferably employed in the form of the stabilized salt, e.g., chlorozincate, borofluoride, etc. The provision of benzene diazonium compounds in the form of stabilized salts is, of course, well established technology being extensively described in the prior art and requires nothing in the way of detailed comment here. Suffice to any that any of the conventional stabilized salt forms are admirably suited for use herein.

The base to which the diazo coating solution is applied may be of any of those conventionally employed for such purposes in the art. Thus, depending upon the application in question, the base in a particular instance may be comprised of a film-forming material, e.g., plastic, cellulose acetate, cellulose acetate buty rate, polyester, polycarbonate and the like; alternatively such base may be of fibrous structure, e.g., highgrade all-sulfide bond paper, cotton, cloth, starch filled cloth, etc. Alternatively, the base may be provided with a suitable protective pre-coating composition for purposes of promoting adhesion of the sensitized layer to the base material. Such embodiments are particularly preferred in those instances wherein difficulty is encountered in achieving the requisite degree of adhesion between the sensitized layer and base material; moreover, such procedures are uniquely advantageous since the pre-coating can serve as a diffusion barrier, thereby further insuring against any possibility of spurious migration of coupling compound, sensitizer or other ingredients of a hydrophilic nature. Suitable pre-coating compositions in this regard include, for example, aqueous dispersion, of polyvinyl acetate, silica, etc. In any event, compositions for such purposes are well known in the art.

The following examples are given for purposes of illustration only and are not to be considered in any as constituting a limitation on the scope of the present invention.

Example 1 An all sulfite bond paper was precoated with the following precoating solution and dried:

Silica 8 g. Polyvinyl acetate emulsion (60 percent solids) 10 Water to cc. The precoat layer was then coated with the following solution and dried:

Water 60 cc.

Glycol 5 cc.

lsopropanol 1 cc.

Citric acid 8 grams Zinc chloride 5 grams Thiourea 5 grams Diresorcyl sulfoxide 1.3 grams Acetoacetanilide 0.26 gram of 26 percent strength 2,3-dihydroxynaphthalene-6 -sulfonic acid 1.8

grams 3-methyl-4-pyrrolydinylbenzene-diazonium chlorozincate 3.2 grams Saponin 0.1 grams Water to 100 cc.

After drying the thus coated paper is exposed to light under a translucent original. Development is effected by subjecting the exposed element to an atmosphere of aqueous ammonia vapors. The reproduction obtained is characterized by high density, excellent contrast and a pronounced neutral black dye image. In contradistinction, repetition of the above example but utilizing as the diazo sensitizer the compound 2,5-dialkoxy-4- morpholino benzenediazonium yields images whose shades are markedly inferior to that obtained in the above example.

Example 2 The procedure described in Example 1 is repeated except that the diresorcyl sulfoxide is replaced by an equimolecular quantity of diresorcyl sulfide. The coupling material 2-hydroxy-3-(N-propylmorpholino)- naphthamide was used in place of the 2,3- dihydroxynaphthalene-6-sulfonic acid. The results obtained are similar to those desxribed above, i.e., superior image reproduction is obtained.

Example 3 Example 1 was repeated with the exception that the 2,3-dihydroxynaphthalene-6-sulfonic acid was replaced by the same weight of 2-hydroxy-3-(N-B- diethylaminoethyl)naphthamide.

Example 4 Example 1 is repeated except that following coating of the sensitized solution upon the sulfide bond paper base, the sensitized element is stored for a period of several months, being subjected throughout such storage to a humid atmosphere. Upon exposure and proceeding as described in Example 1, the image reproduction obtained exhibited each of the improved characteristics, i.e., contrast, density, etc., noted with the above example; it was also noted that spurious diffusion of any of the sensitizing composition ingredients did not occur. If such had been the case, the image obtained would quite obviously exhibit a lack of density and thus covering power, reprint opacity, etc.

Example 5 Example l is repeated except that the coupler mixture includes, additionally, resorcinol. Upon exposure and development, there was obtained an image having excellent contrast and density indicating clearly that the usual tendency of the resorcinol coupled to diffusion into the fibrous base material had been counteracted; apparently, the use of resorcinol in the particular relationship specified herein, i.e., the nature of the coupling components included therewith, influences greatly this property.

Results similar to those described above are obtained when the procedure described are repeated by employing in lieu of the 3-methyl-4-pyrrolidinyl benzenediazonium chlorozincate specifically exemplified, one or more of the following:

3-ethyl-4-pyrrolidinyl benzenediazonium chlorozincate 3-propyl-4-pyrrolidinyl benzenediazonium chlorozincate 3-isobutyl-4-pyrrolidinyl benzenediazonium chlorozincate etc.

It will also be understood that the specific class of diazo sensitizers described herein may be employed in admixtures comprising two or more, depending solely upon the requirements of the processor and of course whether variations in dye shading are desired. In any event, optimum mixtures may be readily ascertained in particular instances by rather routine laboratory investigation. Similar improvement is likewise obtained when the base material employed is non-fibrous in nature, e.g., cellulose acetate, cellulose acetate butyrate, synthetic film-forming polymeric materials, e.g., polyesters such as polyethylene terephthalate, polycarbonates and the like.

It will be further understood that the pyrrolidene moiety of the diazo sensitizer compounds of the present invention may contain additional substituents of an innocuous nature, e.g., alkyl, alkoxy, etc. Accordingly, such substituent derivatives are to be considered equivalents to the compounds specifically enumerated herein. The salient requirement with respect to the nature of such substituents is that they be totally devoid of any tendency to deleteriously effect the spectral response of the diazonium compound or such other vital properties as stability, compatability, and the like.

This invention has been described with respect to certain preferred embodiments and there will become obvious to persons skilled in the art other variations, modifications, and equivalents which are to be understood as coming within the scope of the present invention.

What is claimed is:

1. An ammonia vapor developable diazo sensitizing composition for the production of blackline images consisting essentially of, a mixture of coupling components consisting of an acetoacetamide selected from the group consisting of acetoacetamide, acetoacetanilide, N,N-ethylene-bis-acetoacetamide, acetoacetanaphthylamide, m-hydroxyacetoacetanilide, 0- methylacetoacetanilide, o-methoxyacetoacetanilide, p-methoxyacetoacetanilide, 2-methoxy-5- methylacetoacetanilide, N-(p-methoxybenzyl)- acetoacetamide, N-piperonylacetoacetamide, N-lindonylacetoacetamide, N-(p-methoxyphenethyl)- acetoacetamide, N-benzylacetoacetamide and diacetoacet-dianisidide, a compound selected from the group consisting of a 2-hydroxy-3-(N-lower alkylaminoethyl)-naphthamide and 2,3-dihydroxynaphthalene-G-sulfonic acid and a diresorcyl compound selected from the group consisting of diresorcyl sulfide and diresorcyl sulfoxide, and resorcinol; a 4-N-pyrrolidinyl-3-alkyl benzene diazonium salt wherein the alkyl substituent has from one to four carbon atoms; and an acid stabilizer.

2. A composition according to claim 1 wherein said diazo sensitizing compound is 3-methyl-4-pyrrolidinyl benzene-diazonium chlorozincate.

3. A composition according to claim 1 wherein said diresorcyl is diresorcyl sulfide.

4. A composition according to claim 1 wherein said diresorcyl is diresorcyl sulfoxide.

5. A light sensitive diazotype element for the production of blackline images comprising a base coated with the composition of claim 1.

6. A diazotype element according to claim 5 wherein said base comprises paper.

7. A diazotype element according to claim 5 provided with a pre-coated layer intermediate the base and light sensitive diazo layer.

8. A diazotype element according to claim 5 wherein said pre-coat comprises an aqueous emulsion of polyvinyl acetate and silica. 

2. A composition according to claim 1 wherein said diazo sensitizing compound is 3-methyl-4-pyrrolidinyl benzene-diazonium chlorozincate.
 3. A composition according to claim 1 wherein said diresorcyl is diresorcyl sulfide.
 4. A composition according to claim 1 wherein said diresorcyl is diresorcyl sulfoxide.
 5. A light sensitive diazotype element for the production of blackline images comprising a base coated with the composition of claim
 1. 6. A diazotype element according to claim 5 wherein said base comprises paper.
 7. A diazotype element according to claim 5 provided with a pre-coated layer intermediate the base and light sensitive diazo layer.
 8. A diazotype element according to claim 5 wherein said pre-coat comprises an aqueous emulsion of polyvinyl acetate and silica. 